Nucleic acids encoding a house dust mite allergen Der p III, and uses therefor

ABSTRACT

Isolated nucleic acids encoding an allergen of  Dermatophagoides pteronyssinus , Der p III, are disclosed. A cDNA encoding a peptide having a Der p III activity and a predicted molecular weight of about 24,985 daltons is also described. The nucleic acids can be used as probes to detect the presence of Der p III nucleic acid in a sample or for the recombinant production of peptides having an activity of Der p III. Peptides having an activity of Der p III can be used in compositions suitable for pharmaceutical administration or methods of diagnosing sensitivity to house dust mites.

BACKGROUND OF THE INVENTION

Approximately 10% of the population become hypersensitized (allergic)upon exposure to antigens from a variety of environmental sources. Thoseantigens that induce immediate and/or delayed types of hypersensitivityare known as allergens (King, T. P., (1976) Adv. Immunol., 23:77-105).Allergens can include products of grasses, trees, weeds, animal dander,insects, food, drugs, and chemicals. Genetic predisposition of anindividual is believed to play a role in the development of immediateallergic responses (Young, R. P. et al., (1990) Clin. Sci., 79:19) suchas atopy and anaphylaxis, whose symptoms include hay fever, asthma, andhives.

The antibodies involved in atopic allergy belong primarily to the IgEclass of immunoglobulins. IgE binds to basophils, mast cells anddendritic cells via a specific, high-affinity receptor FcεRI (Kinet, J.P., (1990) Curr. Opin. Immunol., 2:499-505). Upon combination of anallergen acting as a ligand with its cognate receptor IgE, FcεRI boundto the IgE may be cross-linked on the cell surface, resulting inphysiological manifestations of the IgE—allergen interaction. Thesephysiological effects include the release of, among other substances,histamine, serotonin, heparin, chemotactic factor(s) for eosinophilicleukocytes and/or leukotrienes C4, D4, and E4, which cause prolongedconstriction of bronchial smooth muscle cells (Hood, L. E. et al.,Immunology (2nd ed.), The Benjamin/Cumming Publishing Co., Inc. (1984)).Hence, the ultimate consequence of the interaction of an allergen withIgE is allergic symptoms triggered by the release of the aforementionedmediators. Such symptoms may be systemic or local in nature, dependingon the route of entry of the antigen and the pattern of deposition ofIgE on mast cells or basophils. Local manifestations generally occur onepithelial surfaces at the site of entry of the allergen. Systemiceffects can induce anaphylaxis (anaphylactic shock) which results fromIgE-basophil response to circulating (intravascular) antigen.

Studies with purified allergens have shown that about 80% of patientsallergic to the mite Dermatophagoides pteronyssinus produce IgE reactiveto Der p I and Der p II (Chapman M. D. et al., J. Immunol. (1980)125:587-92; Lind P., J. Allergy Clin. Immunol. (1985) 76:753-61; Van derZee J. S. et al, J. Allergy Clin. Immunol. (1988) 81:884-95). For abouthalf the patients these specificities constitute 50% of the IgE antimiteantibody. The allergen Der p III, recently identified as trypsin,(Stewart G. A. et al., Immunology (1992) 75:29-35) reacts with a similaror higher frequency (Stewart G. A. et al, supra; Ford S. A. et al.,Clin. Exp. Allergy (1989) 20:27-31). However, in the only quantitativestudy reported to date, the investigators determined that the level ofIgE binding to Der p III was considerably less than for Der p I.Electrophoretic techniques (Ford S. A. et al., supra; Bengtsson A. etal., Int. Arch. Allergy Appl. Immunol. (1986) 8:383-90; Lind P. et al.,Scand. J. Immunol. (1983) 17:263-73; Tovey E. R. et al., J. AllergyClin. Immunol. (1987) 79:93-102) have shown that most sera contain IgEwhich recognize other allergens.

The significance of the IgE reactivity to Der p III remains uncertain.The reactivity of this group of allergens has been reported to be as lowas 16% using a fluid phase assay (Heymann et al., J Allergy Clin Immunol(1989) 83: 1055-1067) and as high as 100% using RAST assay (Stewart etal., Immunology (1992) 75: 29-35). Several others have reported IgEreactivity between 60-83% (Tovey etal., J Allergy Clin Immunol (1987)22: 93-102; Thomas et al., Exp Appl Acarol (1992) 16: 153-164; Yasuedaet al., Clin Exp Allergy (1993) 23:384-390). The discrepancies in thefrequency of IgE reactivity to the group III allergens may beattributable to either the differences in the purity of the allergenpreparation studied or the differences in sensitivity of the assaytechniques used. In order to determine the importance of particularspecificities in the allergic reactions, there is a need for quantitiesof pure allergen, which would enable quantitative IgE binding tests andstudies of the frequency and lymphokine profile of T cell responses tothe allergen.

Many patients with sensitivity to house dust mite allergens are treatedcurrently by administration of small, gradually increasing doses ofhouse dust mite extracts. Use of these extracts has multiple drawbacks,including potential anaphylaxis during treatment and the necessity ofcontinuing therapy, often for a period of several years to build upsufficient tolerance and significant diminution of clinical symptoms.The ability to substitute compositions of house dust mite allergen, Derp III, would overcome several of these drawbacks. Thus, a source of pureallergen that could be provided in quantity for use as a diagnostic ortherapeutic reagent and therapeutic methods that would overcome thedrawbacks associated with house dust mite extracts are highly desirable.

SUMMARY OF INVENTION

This invention provides isolated nucleic acids encoding peptides havingat least one biological activity of Der p III, an allergen of thespecies Dermatophagoides pteronyssinus (house dust mite). A preferrednucleic acid is a cDNA having a nucleotide sequence shown in FIG. 1 (SEQID NO:1). The invention also pertains to peptides encoded by all or aportion of such cDNA (SEQ ID NO: 1) and having at least one biologicalactivity of Der p III. Also contemplated are isolated nucleic acidswhich hybridize under high stringency conditions (e.g., equivalent to20-27° C. below T_(m) and 1M NaCl ) to a nucleic acid having anucleotide sequence shown in FIG. 1 (SEQ ID NO: 1) or which encodes apeptide comprising all or a portion of an amino acid sequence of FIG. 1(SEQ ID NO:2). Nucleic acids which encode peptides having an activity ofDerp III and having at least 50% homology with a sequence shown in FIG.1 (SEQ ID NO:2) are also featured. Peptides having a Der p III activityproduced by recombinant expression of a nucleic acid of the invention,and peptides having a Der p III activity prepared by chemical synthesisare also featured by this invention. Preferred peptides have the abilityto induce a T cell response which can include T cell stimulation(measured by, for example, T cell proliferation or cytokine secretion)or T cell non-responsiveness (i.e., contact with the peptide or acomplex of the peptide with an MHC molecule of an antigen presentingcell induces the T cell to become unresponsive to stimulatory signals orincapable of proliferation). Other preferred peptides either apart fromor in addition to the ability to induce a T cell response, have theability to bind specific IgE of house dust mite-allergic subjects. Suchpeptides are useful in diagnosing sensitivity to house dust mites in asubject. Still other peptides, either apart from or in addition to theability to induce a T cell response, have a significantly reduced ornegligible ability to bind house dust mite-allergic IgE. Such peptidesare particularly useful as therapeutic agents.

Other preferred peptides comprise an amino acid sequence shown in FIG. 1(SEQ ID NO:2). In one embodiment, peptides having a Derp III activityand comprising a portion of the amino acid sequence of FIG. 1 (SEQ IDNO:2) are at least about 8-30 amino acids in length, preferably about10-20 amino acids in length, and most preferably about 10-16 amino acidsin length.

Another aspect of the invention features antibodies specificallyreactive with peptides having a Der p III activity. Peptides having anactivity of Der p III can be used in compositions suitable forpharmaceutical administration. For example, such compositions can beused in a manner similar to house dust mite extracts to treat or preventallergic reactions to house dust mites in a subject. Nucleic acids ofthe invention and peptides having an activity of Der p III can also beused for diagnosing sensitivity in a subject to house dust mites.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the complete nucleotide (SEQ ID NO:1) and deduced aminoacid (SEQ ID NO:2) sequences of the Der p III clone.

FIG. 2 shows the amino acid sequences of Der p III (SEQ ID NO:2) and atrypsin protein from crayfish (SEQ ID NO:3).

FIG. 3 shows the results of SDS-PAGE analysis of various concentrationsof recombinant Der p III (lane 1, 4.3 μg; lane 2, 8.7 μg; lane 3, 13.8μg; lane 4, 17.4 μg; markers are indicated by M).

DETAILED DESCRIPTION OF THE INVENTION

This invention pertains to isolated nucleic acids encoding peptideshaving at least one biological activity of Derp III, a Group IIIallergen of the species Dermatophagoides pteronyssinus. Preferably, thenucleic acid is a cDNA comprising a nucleotide sequence shown in FIG. 1(SEQ ID NO:1).

The cDNA shown in FIG. 1 (SEQ ID NO: 1) encodes a Der p III peptidewhich includes a predicted 29 amino acid residue pre-pro region encodedby nucleotides 63 through 149. This leader sequence is not found in themature Der p III which is encoded by nucleotides 150 through 845. Thededuced amino acid sequence based on this cDNA is also shown in FIG. 1(SEQ ID NO:2). The cDNA encodes a 232 residue mature peptide having apredicted molecular weight of 24,985 daltons including seven cysteineresidues. A polyadenylation signal sequence 179 nucleotides after thelast base is present in the cDNA (See FIG. 1). A culture of E. colitransfected with an expression vector containing the cDNA encoding Der pIII was deposited under the Budapest Treaty with the American TypeCulture Collection on Oct. 15, 1993 and assigned accession number 69472.

Accordingly, one aspect of this invention pertains to isolated nucleicacids comprising a nucleotide sequence encoding Der p III, fragmentsthereof encoding peptides having at least one biological activity of Derp III and/or equivalents of such nucleic acids. The term nucleic acid asused herein is intended to include such fragments and equivalents. Theterm equivalent is intended to include nucleotide sequences encodingfunctionally equivalent Der p III peptides having an activity of Der pIII. As defined herein, a peptide having an activity of Der p III has atleast one biological activity of the Der p III allergen. Equivalentnucleotide sequences include sequences that differ by one or morenucleotide substitutions, additions or deletions, such as allelicvariants, and include sequences that differ from the nucleotide sequenceencoding Der p III shown in FIG. 1 (SEQ ID NO: 1) due to the degeneracyof the genetic code. Equivalents includes nucleotide sequences thathybridize under stringent conditions (i.e., equivalent to about 20-27°C. below melting temperature (T_(m)) and about 1M NaCl) to thenucleotide sequence of Der p III shown in FIG. 1 (SEQ ID NO:1).

Peptides referred to herein as having an activity of Der p III or havinga Der p III activity are defined herein as peptides that have an aminoacid sequence corresponding to all or a portion of the amino acidsequence of Derp III shown in FIG. 1 (SEQ ID NO:2). For example, apeptide having an activity of Der p III may have the ability to induce aresponse in Der p III restricted T cells such as stimulation (e.g., Tcell proliferation or cytokine secretion) or induce T cellnon-responsiveness. Alternatively, or additionally, a peptide having anactivity of Der p III may have the ability to bind (to be recognized by)immunoglobulin E antibodies of house dust mite-allergic subjects.Peptides which bind IgE are useful in methods of detecting allergicsensitivity to Der p III in a subject. Peptides that do not bind IgE, orbind IgE to a lesser extent than a purified, native Der p III proteinbinds IgE are particularly useful as therapeutic agents.

In one embodiment, the nucleic acid is a cDNA encoding a peptide havingan activity of Der p III. Preferably, the nucleic acid is a cDNAmolecule comprising at least a portion of the nucleotide sequenceencoding Der p III shown in FIG. 1 (SEQ ID NO: 1). A preferred portionof the cDNA molecule of FIG. 1 (SEQ ID NO: 1) includes the coding regionof the molecule.

In another embodiment, the nucleic acid of the invention encodes apeptide having an activity of Der p III and comprising an amino acidsequence shown in FIG. 1 (SEQ ID NO:2). Preferred nucleic acids encode apeptide having a Derp III activity and having at least about 50%homology, more preferably at least about 60% homology and mostpreferably at least about 70% homology with the sequence shown in FIG. 1(SEQ ID NO:2). Nucleic acids which encode peptides having a Derp IIIactivity and having at least about 90%, more preferably at least about95%, and most preferably at least about 98-99% homology with a sequenceset forth in FIG. 1 (SEQ ID NO:2) are also within the scope of theinvention. Homology refers to sequence similarity between two peptideshaving an activity of Der p III or between two nucleic acid molecules.Homology can be determined by comparing a position in each sequencewhich may be aligned for purposes of comparison. When a position in thecompared sequence is occupied by the same base or amino acid, then themolecules are homologous at that position. A degree of homology betweensequences is a function of the number of matching or homologouspositions shared by the sequences.

Another aspect of the invention provides a nucleic acid that hybridizesunder high or low stringency conditions to a nucleic acid encoding apeptide having all or a portion of an amino acid sequence shown in FIG.1 (SEQ ID NO:2). Appropriate stringency conditions which promote DNAhybridization, for example, 6.0× sodium chloride/sodium citrate (SSC) atabout 45° C., followed by a wash of 2.0×SSC at 50° are known to thoseskilled in the art or can be found in Current Protocols in MolecularBiology, John Wiley & Sons, N.Y. (1989), 6.3.1-6.3.6. For example, thesalt concentration in the wash step can be selected from a lowstringency of about 2.0×SSC at 50° C. to a high stringency of about0.2×SSC at 50° C.. In addition, the temperature in the wash step can beincreased from low stringency conditions at room temperature, about 22°C., to high stringency conditions at about 65° C.

Isolated nucleic acids encoding a peptide having an activity of Der pIII, as described herein, and having a sequence that differs from thenucleotide sequence shown in FIG. 1 (SEQ ID NO: 1) due to degeneracy inthe genetic code are also within the scope of the invention. Suchnucleic acids differ in sequence from the sequence of FIG. 1 (SEQ IDNO: 1) encode functionally equivalent peptides (i.e., peptides having anactivity of Der p III), but due to degeneracy in the genetic code. Forexample, a number of amino acids are designated by more than onetriplet. Codons that specify the same amino acid, or synonyms (forexample, CAU and CAC are synonyms for histidine) may result in “silent”mutations that do not affect the amino acid sequence of the Der p IIIprotein. However, it is expected that DNA sequence polymorphisms that dolead to changes in the amino acid sequence of Der p III will existwithin the house dust mite population. One skilled in the art willappreciate that these variations in one or more nucleotides (up to about3-4% of the nucleotides) of the nucleic acids encoding peptides havingan activity of Der p III may exist among individual house dust mites dueto natural allelic variation. Any and all such nucleotide variations andresulting amino acid polymorphisms are within the scope of thisinvention. Furthermore, there may be one or more isoforms or related,cross-reacting family members of Derp III. Such isoforms or familymembers are defined as proteins related in function and amino acidsequence to Der p III, but are encoded by genes at different loci.

Fragments of a nucleic acid encoding Der p III are also within the scopeof the invention. As used herein, a fragment of a nucleic acid encodingDer p III refers to a nucleotide sequence having fewer nucleotides thanthe nucleotide sequence encoding the entire amino acid sequence of Der pIII protein and which encodes a peptide having an activity of Der p III(i.e., a peptide having at least one biological activity of the Der pIII allergen) as defined herein.

Preferred nucleic acid fragments encode peptides of at least 10 aminoacid residues in length, preferably about 10-20 amino acid residues inlength, and more preferably about 10-16 amino acid residues in length.Nucleic acid fragments that encode peptides having a Der p III activityof at least about 30 amino acid residues in length, at least about 40amino acid residues in length, at least about 60 amino acid residues inlength, at least about 80 amino acid residues in length, at least about100 amino acid residues in length, and at least about 200 amino acidresidues in length or more are also within the scope of this invention.

Nucleic acid fragments within the scope of the invention include thosecapable of hybridizing under high or low stringency with nucleic acidsfrom other animal species for use in screening protocols to detect Der pIII or allergens that are cross-reactive with Der p III. Generally, thenucleic acid encoding a peptide having an activity of Derp III will beselected from the bases encoding the mature protein, however, in someinstances, it may be desirable to select all or part of a peptide fromthe leader sequence portion of the nucleic acid of the invention.Nucleic acids within the scope of the invention may also contain linkersequences, modified restriction endonuclease sites and other sequencesuseful for molecular cloning, expression or purification of recombinantpeptides having an activity of Der p III.

A nucleic acid encoding a peptide having an activity of Der p III may beobtained from mRNA present in house dust mites of the speciesDermatophagoides pteronyssinus. It should also be possible to obtainnucleic acids encoding Der p III from Dermatophagoides pteronyssinusgenomic DNA. For example, the gene encoding Der p III can be cloned fromeither a cDNA or a genomic library in accordance with protocols hereindescribed. A cDNA encoding Der p III can be obtained by isolating totalmRNA from Dermatophagoides pteronyssinus. Double stranded cDNAs can thenbe prepared from the total mRNA. Subsequently, the cDNAs can be insertedinto a suitable plasmid or bacteriophage vector using any one of anumber of known techniques. Genes encoding Der p III can also be clonedusing established polymerase chain reaction techniques in accordancewith the nucleotide sequence information provided by the invention. Thenucleic acids of the invention can be DNA or RNA. A preferred nucleicacid is a cDNA encoding Der p III having the sequence depicted in FIG. 1(SEQ ID NO: 1).

This invention also provides expression vectors containing a nucleicacid encoding a peptide having an activity of Der p III operably linkedto at least one regulatory sequence. Operably linked is intended to meanthat the nucleotide sequence is linked to a regulatory sequence in amanner which allows expression of the nucleotide sequence. Regulatorysequences are art-recognized and are selected to direct expression ofthe peptide having an activity of Der p III by a transfected host cell.Accordingly, the term regulatory sequence includes promoters, enhancersand other expression control elements. Such regulatory sequences aredescribed in Goeddel, Gene Expression Technology: Methods in Enzymology185, Academic Press, San Diego, Calif. (1990). It should be understoodthat the design of the expression vector may depend on such factors asthe choice of the host cell to be transformed and/or the type of proteindesired to be expressed. In one embodiment, the expression vectorincludes a DNA encoding a peptide having an activity of Der p III. Suchexpression vectors can be used to transfect cells to thereby produceproteins or peptides, including fusion proteins or peptides encoded bynucleic acids as described herein.

This invention further pertains to a host cell transfected to express apeptide having an activity of Derp III. The host cell may be anyprocaryotic or eucaryotic cell. For example, a peptide having anactivity of Der p III may be expressed in bacterial cells such as E.coli, insect cells (baculovirus), yeast, or mammalian cells such asChinese hamster ovary cell (CHO). Other suitable host cells are referredto in Goeddel (1990), supra, or known to those skilled in the art.

Expression in eucaryotic cells such as mammalian, yeast, or insect cellscan lead to partial or complete glycosylation and/or formation ofrelevant inter- or intra-chain disulfide bonds of a recombinant peptideproduct. Examples of vectors for expression in yeast S. cerivisaeinclude pYepSec1 (Baldari. et al., (1987) Embo J. 6:229-234), pMFa(Kurjan and Herskowitz, (1982) cell 30:933-943), pJRY88 (Schultz et al,(1987) Gene 54:113-123), and pYES2 (Invitrogen Corporation, San Diego,Calif.). Baculovirus vectors available for expression of proteins incultured insect cells (SF 9 cells) include the pAc series (Smith et al.,(1983) Mol. Cell Biol. 2:2156-2165) and the pVL series (Lucklow, V. A.,and Summers, M. D., (1989) Virology 170:31-39). Generally, COS cells(Gluzman, Y., (1981) Cell 2:175-182) are used in conjunction with suchvectors as pCDM 8 (Aruffo, A. and Seed, B., (1987) Proc. Natl. Acad.Sci. USA 84:8573-8577) for transient amplification/expression inmammalian cells, while CHO (dhfr⁻ Chinese Hamster Ovary) cells are usedwith vectors such as pMT2PC (Kaufman et al., (1987), EMBO J. 6:187-195)for stable amplification/expression in mammalian cells. Vector DNA canbe introduced into mammalian cells via conventional techniques such ascalcium phosphate or calcium chloride co-precipitation,DEAE-dextran-mediated transfection, or electroporation. Suitable methodsfor transforming host cells can be found in Sambrook et al. (MolecularCloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor Laboratorypress (1989)), and other laboratory textbooks.

Expression in procaryotes is most often carried out in E. coli witheither fusion or non-fusion inducible expression vectors. Fusion vectorsusually add a number of NH₂ terminal amino acids to the expressed targetgene. These NH₂ terminal amino acids often are referred to as a reportergroup. Such reporter groups usually serve two purposes: 1) to increasethe solubility of the target recombinant protein; and 2) to aid in thepurification of the target recombinant protein by acting as a ligand inaffinity purification. Often, in fusion expression vectors, aproteolytic cleavage site is introduced at the junction of the reportergroup and the target recombinant protein to enable separation of thetarget recombinant protein from the reporter group subsequent topurification of the fusion protein. Such enzymes, and their cognaterecognition sequences, include Factor Xa, thrombin and enterokinase.Typical fusion expression vectors include pGEX (Amrad Corp., Melbourne,Australia), pMAL (New England Biolabs, Beverly, Mass.) and pRIT5(Pharmacia, Piscataway, N.J.) which fuse glutathione S-transferase,maltose E binding protein, or protein A, respectively, to the targetrecombinant protein. A preferred reporter group is poly(His), whichrenders the recombinant fusion protein easily purifiable by metalchelate chromatography.

Inducible non-fusion expression vectors include pTrc (Amann et al.,(1988) Gene 69:301-315) and pET11d (Studier et al., Gene ExpressionTechnology: Methods in Enzymology 185, Academic Press, San Diego, Calif.(1990) 60-89). While target gene expression relies on host RNApolymerase transcription from the hybrid trp-lac fusion promoter inpTrc, expression of target genes inserted into pET11d relies ontranscription from the T7 gn10-lac 0 fusion promoter mediated bycoexpressed viral RNA polymerase (T7 gn1). This viral polymerase issupplied by host strains BL21(DE3) or HMS174(DE3) from a resident λprophage harboring a T7 gn1 under the transcriptional control of thelacUV 5 promoter.

One strategy to maximize recombinant Der p III expression in E. coli isto express the protein in a host bacteria with an impaired capacity toproteolytically cleave the recombinant protein (Gottesman, S., GeneExpression Technology: Methods in Enzmology 185, Academic Press, SanDiego, Calif. (1990) 119-128). Another strategy would be to alter thenucleic acid encoding Der p III to be inserted into an expression vectorso that the individual codons for each amino acid would be thosepreferentially utilized in highly expressed E. coli proteins (Wada etal, (1992) Nuc. Acids Res. 20:2111-2118). Such alteration of nucleicacids of the invention can be carried out by standard DNA synthesistechniques.

The nucleic acids of the invention can also be chemically synthesizedusing standard techniques. Various methods of chemically synthesizingpolydeoxynucleotides are known, including solid-phase synthesis which,like peptide synthesis, has been fully automated in commerciallyavailable DNA synthesizers (See, e.g., Itakura et al., U.S. Pat. No.4,598,049; Caruthers et al., U.S. Pat. No. 4,458,066; and Itakura U.S.Pat. Nos. 4,401,796 and 4,373,071, incorporated by reference herein).

The present invention further pertains to methods of producing peptidesthat have an activity of Der p III. For example, a host cell transfectedwith a nucleic acid vector directing expression of a nucleotide sequenceencoding a peptide having an activity of Der p III can be cultured underappropriate conditions to allow expression of the peptide to occur. Thepeptide may be secreted and isolated from a mixture of cells and mediumcontaining the peptide. Alternatively, the peptide may be retainedcytoplasmically and the cells harvested, lysed and the protein isolated.A cell culture includes host cells, media and other byproducts. Suitablemedia for cell culture are well known in the art. Peptides of theinvention can be isolated from cell culture medium, host cells, or bothusing techniques known in the art for purifying proteins includingion-exchange chromatography, gel filtration chromatography,ultrafiltration, electrophoresis, and immunoaffinity purification withantibodies specific for such peptides.

Another aspect of the invention pertains to isolated peptides having anactivity of Der p III. A peptide having an activity of Der p III has atleast one biological activity of the Der p III allergen. For example, apeptide having an activity of Derp III may have the ability to induce aresponse in Der p III specific T cells such as stimulation (T cellproliferation or cytokine secretion) or induce T cellnon-responsiveness. In one embodiment, a peptide having an activity ofDer p III stimulates T cells as evidenced by, for example, T cellproliferation or cytokine secretion. In another embodiment, peptideshaving a Der p III activity induce T cell non-responsiveness in which Tcells are unresponsive to a subsequent challenge with a Der p IIIpeptide or native Der p III protein following exposure to the peptide.In yet another embodiment, a peptide having a Derp III activity hasreduced IgE binding activity compared to purified, native Der p IIIprotein. A peptide having an activity of Der p III may differ in aminoacid sequence from the Der p III sequence depicted in FIG. 1 (SEQ IDNO:2) but such differences result in a modified protein which functionsin the same or similar manner as a native Der p III protein or which hasthe same or similar characteristics of Der p III protein. Variousmodifications of the Der p III protein to produce these and otherfunctionally equivalent peptides are described in detail herein. Theterm peptide, as used herein, refers to peptides, proteins, andpolypeptides.

A peptide can be produced by modification of the amino acid sequence ofthe Der p III protein shown in FIG. 1 (SEQ ID NO:2), such as by asubstitution, addition, or deletion of one or more amino acid residues.Such modifications may be directed to amino acid residues not involvedin a biological activity of the peptide, or the modifications may bedirected to such amino acid residues in order to enhance, or eliminate aparticular biological activity. Peptides of the invention are at leastabout 8 amino acid residues in length, preferably about 10-20 amino acidresidues in length and more preferably about 10-16 amino acid residuesin length. Peptides having an activity of Derp III of at least about 30amino acid residues in length, at least about 40 amino acid residues inlength, at least about 60 amino acid residues in length, at least about80 amino acid residues in length, at least about 100 amino acid residuesin length, and at least about 200 amino acid residues or more in lengthare also included within the scope of this invention.

In another embodiment of the invention, peptides from a related GroupIII allergen of the species Dermatophagoides farinae, Der f III, areprovided. Such peptides have been isolated from a purified, native Der fIII protein and comprise the sequences: IVGGVKAKAGDSPYQISLQSSSHFXGGSILD(SEQ ID NO: 15), an N-terminal sequence; MICGGDVANGGVDSEQGD (SEQ ID NO:10), an internal peptide; and MTLDQTNAKPVPLPTS (SEQ ID NO:12), aninternal peptide.

Yet another embodiment of the invention provides a substantially purepreparation of a peptide having an activity of Der p III. Such apreparation is substantially free of proteins and peptides with whichthe peptide naturally occurs (i.e., other house dust mite peptides),either in a cell or when secreted by a cell.

The term isolated as used herein refers to a nucleic acid or peptidethat is substantially free of cellular material or culture medium whenproduced by recombinant DNA techniques, or chemical precursors or otherchemicals when chemically synthesized. Such peptides are alsocharacterized as being free of all other house dust mite proteins.Accordingly, an isolated peptide having an activity of Der p III isproduced recombinantly or synthetically and is substantially free ofcellular material and culture medium or substantially free of chemicalprecursors or other chemicals and is free of all other house dust miteproteins. An isolated nucleic acid is also free of sequences whichnaturally flank the nucleic acid (i.e., sequences located at the 5′ and3′ ends of the nucleic acid) in the organism from which the nucleic acidis derived.

Peptides having an activity of Der p III can be obtained, for example,by screening peptides recombinantly produced from the correspondingfragment of the nucleic acid of Der p III encoding such peptides. Inaddition, fragments can be chemically synthesized using techniques knownin the art such as conventional Merrifield solid phase f-Moc or t-Bocchemistry. For example, the Derp III protein may be arbitrarily dividedinto fragments of desired length with no overlap of the fragments, orpreferably divided into overlapping fragments of a desired length. Thefragments can be produced (recombinantly or by chemical synthesis) andtested to identify those peptides having a Derp III activity, i.e., theability to induce a T cell response such as T cell stimulation (T cellproliferation, cytokine secretion) or T cell non-responsiveness, and/orhas reduced IgE binding activity.

In one embodiment, peptides having an activity of Der p III can beidentified by the ability of the peptide to stimulate T cells or toinduce T cell non-responsiveness. Peptides which stimulate T cells, asdetermined by, for example, T cell proliferation or cytokine secretionare defined herein as comprising at least one T cell epitope. T cellepitopes are believed to be involved in initiation and perpetuation ofthe immune response to the protein allergen which is responsible for theclinical symptoms of allergy. These T cell epitopes are thought totrigger early events at the level of the T helper cell by binding to anappropriate HLA molecule on the surface of an antigen presenting cell,thereby stimulating the T cell subpopulation with the relevant T cellreceptor for the epitope. These events lead to T cell proliferation,lymphokine secretion, local inflammatory reactions, recruitment ofadditional immune cells to the site of antigen/T cell interaction, andactivation of the B cell cascade, leading to the production ofantibodies. One isotype of these antibodies, IgE, is fundamentallyimportant to the development of allergic symptoms and its production isinfluenced early in the cascade of events at the level of the T helpercell, by the nature of the lymphokines secreted. A T cell epitope is thebasic element, or smallest unit of recognition by a T cell receptor,where the epitope comprises amino acids essential to receptorrecognition. Amino acid sequences which mimic those of the T cellepitopes and which modify the allergic response to protein allergens arewithin the scope of this invention.

Screening peptides for those which retain a Der p III activity asdescribed herein can be accomplished using one or more of severaldifferent assays. For example, in vitro, Derp III T cell stimulatoryactivity is assayed by contacting a peptide known or suspected of havinga Der p III activity with an antigen presenting cell which presentsappropriate MHC molecules in a T cell culture. Presentation of a peptidehaving a Der p III activity in association with appropriate MHCmolecules to T cells in conjunction with the necessary costimulation hasthe effect of transmitting a signal to the T cell that induces theproduction of increased levels of cytokines, particularly ofinterleukin-2 and interleukin-4. The culture supernatant can be obtainedand assayed for interleukin-2 or other known cytokines. For example, anyone of several conventional assays for interleukin-2 can be employed,such as the assay described in Proc. Natl. Acad. Sci USA, 86:1333(1989), the pertinent portions of which are incorporated herein byreference. A kit for an assay for the production of interferon is alsoavailable from Genzyme Corporation (Cambridge, Mass.).

Alternatively, a common assay for T cell proliferation entails measuringtritiated thymidine incorporation. The proliferation of T cells can bemeasured in vitro by determining the amount of ³H-labeled thymidineincorporated into the replicating DNA of cultured cells. Therefore, therate of DNA synthesis and, in turn, the rate of cell division can bequantified.

In another embodiment, a peptide having a Der p III activity is screenedfor the ability to induce T cell non-responsiveness. The ability of apeptide known to stimulate T cells (as determined by one or more of theabove described assays) to inhibit or completely block the activity ofpurified native Der p III or portion thereof and induce a state ofnon-responsiveness can be determined using subsequent attempts atstimulation of the T cells with antigen presenting cells that presentnative Der p III, or a peptide having a Der p III activity, followingexposure to the peptide having a Der p III activity. If the T cells areunresponsive to the subsequent activation attempts, as determined byinterleukin-2 synthesis and/or T cell proliferation, a state ofnon-responsiveness has been induced. See, e.g., Gimmi, et al. (1993)Proc. Natl. Acad. Sci USA, 90:6586-6590; and Schwartz (1990) Science,248:1349-1356, for assay systems that can be used as the basis for anassay in accordance with the present invention.

In yet another embodiment, peptides having a Derp III activity areidentified by IgE binding activity. For therapeutic purposes, peptidesof the invention preferably do not bind IgE specific for a house dustmite allergen or bind such IgE to a substantially lesser extent than thepurified, native house dust mite allergen binds such IgE. Reduced IgEbinding activity refers to IgE binding activity that is less than thatof purified, native Derp III protein. If a peptide having a Der p IIIactivity is to be used as a diagnostic reagent, it is not necessary thatthe peptide have reduced IgE binding activity compared to the native Derp III allergen. IgE binding activity of peptides can be determined, forexample, by an enzyme-linked immunosorbent assay (ELISA) using, forexample, sera obtained from a subject (i.e., an allergic subject) thathas been previously exposed to the native Derp III allergen. Briefly,the peptide suspected of having a Der p III activity is coated ontowells of a microtiter plate. After washing and blocking the wells,antibody solution consisting of the plasma of an allergic subject whohas been exposed to a peptide suspected of having a Derp III activity isincubated in the wells. The plasma is generally depleted of IgG beforeincubation. A labeled secondary antibody is added to the wells andincubated. The amount of IgE binding is then quantified and compared tothe amount of IgE bound by a purified, native Der p III protein.Alternatively, the IgE binding activity of a peptide can be determinedby Western blot analysis. For example, a peptide suspected of having aDer p III activity is run on a polyacrylamide gel using SDS-PAGE. Thepeptide is then transferred to nitrocellulose and subsequently incubatedwith sera from an allergic subject. After incubation with a labeledsecondary antibody, the amount of IgE bound is then determined andquantified.

Another assay which can be used to determine the IgE binding activity ofa peptide is a competition ELISA assay. Briefly, an IgE antibody pool isgenerated by combining plasma from house dust mite allergic subjectsthat have been shown by direct ELISA to have IgE reactive with nativeDer p III. This pool is used in ELISA competition assays to compare IgEbinding of native Derp III and a peptide suspected of having a Derp IIIactivity. IgE binding for the native Der p III and a peptide suspectedof having a Der p III activity is determined and quantified.

If a peptide having an activity of Der p III binds IgE and is to be usedas a therapeutic agent, it is preferable that such binding does notresult in the release of mediators (e.g., histamines) from mast cells orbasophils. To determine whether a peptide which binds IgE results in therelease of mediators, a histamine release assay can be performed usingstandard reagents and protocols obtained from Amac, Inc. (Westbrook,Me.). Briefly, a buffered solution of a peptide suspected of having aDer p III activity is combined with an equal volume of whole heparinizedblood from an allergic subject. After mixing and incubation, the cellsare pelleted and the supernatants are processed and analyzed using aradioimmunoassay to determine the amount of histamine released.

Peptides having an activity of Der p III which are to be used astherapeutic agents are preferably tested in mammalian models of housedust mite atopy, such as the mouse model disclosed in Tamura et al.,(1986) Microbiol. Immunol. 3:883-896, or in U.S. Pat. No. 4,939,239, orin the primate model disclosed in Chiba et al., (1990) Int. Arch.Allergy Immunol. 93:83-88. Initial screening for IgE binding to apeptide having an activity of Der p III may be performed by scratchtests or intradermal skin tests on laboratory animals or humanvolunteers, or in in vitro systems such as RAST, RAST inhibition, ELISAassay, RIA (radioimmunoassay), or a histamine release assay, asdescribed above.

It is possible to modify the structure of a peptide having an activityof Der p III for such purposes as increasing solubility, enhancingtherapeutic or prophylactic efficacy, or stability (e.g., shelf life exvivo and resistance to proteolytic degradation in vivo). Such modifiedpeptides are considered functional equivalents of peptides having anactivity of Der p III as defined herein. A modified peptide can beproduced in which the amino acid sequence has been altered, such as byamino acid substitution, deletion, or addition, to modify immunogenicityand/or reduce allergenicity, or to which a component has been added forthe same purpose.

For example, a peptide having an activity of Der p III can be modifiedso that it maintains the ability to induce T cell non-responsiveness andbind MHC proteins without the ability to induce a strong proliferativeresponse or, possibly, any proliferative response when administered inimmunogenic form. In this instance, critical binding residues for T cellreceptor function can be determined using known techniques (e.g.,substitution of each residue and determination of the presence orabsence of T cell reactivity). Those residues shown to be essential forinteraction with the T cell receptor can be modified by replacing theessential amino acid with another, preferably similar amino acid residue(a conservative substitution) whose presence is shown to enhance,diminish but not eliminate, or not affect T cell reactivity. Inaddition, those amino acid residues which are not essential for T cellreceptor interaction can be modified by being replaced by another aminoacid whose incorporation may enhance, diminish but not eliminate, or notaffect T cell reactivity, but whose incorporation does not eliminatebinding to relevant MHC.

Additionally, a peptide having an activity of Der p III can be modifiedby replacing an amino acid shown to be essential for interaction withthe MHC protein complex with another, preferably similar amino acidresidue (conservative substitution) whose presence is shown to enhance,diminish but not eliminate or affect T cell activity. In addition, aminoacid residues which are not essential for interaction with the MHCprotein complex but which still bind the MHC protein complex can bemodified by being replaced by another amino acid whose incorporation mayenhance, not affect, or diminish but not eliminate T cell reactivity.Preferred amino acid substitutions for non-essential amino acidsinclude, but are not limited to substitutions with alanine, glutaricacid, or a methyl amino acid.

Another example of modification of a peptide having an activity of Der pIII is substitution of cysteine residues preferably with alanine,serine, threonine, leucine or glutamic acid residues to minimizedimerization via disulfide linkages. In addition, amino acid side chainsof peptides of the invention can be chemically modified. Anothermodification is cyclization of the peptide.

In order to enhance stability and/or reactivity, a peptide having anactivity of Der p III can be modified to incorporate one or morepolymorphisms in the amino acid sequence of the protein allergenresulting from any natural allelic variation. Additionally, D-aminoacids, non-natural amino acids, or non-amino acid analogs can besubstituted or added to produce a modified protein within the scope ofthis invention. Furthermore, a peptide having an activity of Der p IIIcan be modified using polyethylene glycol (PEG) according to the methodof A. Sehon and co-workers (Wie et al., supra) to produce a proteinconjugated with PEG. In addition, PEG can be added during chemicalsynthesis of the protein. Other modifications of a peptide having anactivity of Der p III include reduction/alkylation (Tarr, Methods ofProtein Microcharacterization, J. E. Silver ed., Humana Press, CliftonN.J. 155-194 (1986)); acylation (Tarr, supra); chemical coupling to anappropriate carrier (Mishell and Shiigi, eds., Selected Methods inCellular Immunology, W H Freeman, San Francisco, Calif. (1980), U.S.Pat. No. 4,939,239; or mild formalin treatment (Marsh (1971), Int. Arch.of Allergy and Appl. Immunol. 41:199-215).

To facilitate purification and potentially increase solubility of apeptide having an activity of Der p III, it is possible to add an aminoacid fusion moiety to the peptide backbone. For example, hexa-histidinecan be added to the protein for purification by immobilized metal ionaffinity chromatography (Hochuli, E. et al., (1988) Bio/Technology6:1321-1325). In addition, to facilitate isolation of peptides free ofirrelevant sequences, specific endoprotease cleavage sites can beintroduced between the sequences of the fusion moiety and the peptide.In order to successfully desensitize a subject to Der p III protein orrelated allergen, it may be necessary to increase the solubility of theprotein by adding functional groups to the protein or by omittinghydrophobic regions of the protein.

To potentially aid proper antigen processing of T cell epitopes withinDer p III, canonical protease sensitive sites can be engineered betweenregions, each comprising at least one T cell epitope via recombinant orsynthetic methods. For example, charged amino acid pairs, such as KK orRR, can be introduced between regions within a protein or fragmentduring recombinant construction thereof. The resulting peptide can berendered sensitive to cleavage by cathepsin and/or other trypsin-likeenzymes which would generate portions of the protein containing one ormore T cell epitopes. In addition, such charged amino acid residues canresult in an increase in the solubility of the peptide.

Site-directed mutagenesis of a nucleic acid encoding a peptide having anactivity of Der p III can be used to modify the structure of the peptideby methods known in the art. Such methods may, among others, includepolymerase chain reaction (PCR) with oligonucleotide primers bearing oneor more mutations (Ho et al., (1989) Gene 77:51-59) or total synthesisof mutated genes (Hostomsky, Z. et al., (1989) Biochem. Biophys. Res.Comm 161: 1056-1063). To enhance recombinant protein expression, theaforementioned methods can be applied to change the codons present inthe cDNA sequence of the invention to those preferentially utilized bythe host cell in which the recombinant protein is being expressed (Wadaet al, supra).

Another aspect of the invention pertains to an antibody specificallyreactive with a peptide having an activity of Der p III. The antibodiesof this invention can be used to standardize allergen extracts or toisolate the naturally-occurring or native form of Der p III. Forexample, by using peptides having an activity of Derp III based on thecDNA sequence of Der p III, anti-protein/anti-peptide antisera ormonoclonal antibodies can be made using standard methods. A mammal suchas a mouse, a hamster or a rabbit can be immunized with an immunogenicform of the peptide (e.g., Der p III protein or an antigenic fragmentwhich is capable of eliciting an antibody response). Techniques forconferring immunogenicity on a protein or peptide include conjugation tocarriers or other techniques are well known in the art. A peptide havingan activity of Der p III can be administered in the presence ofadjuvant. The progress of immunization can be monitored by detection ofantibody titers in plasma or serum. Standard ELISA or other immunoassayscan be used with the immunogen as antigen to assess the levels ofantibodies.

Following immunization, anti-Derp III antisera can be obtained and, ifdesired, polyclonal anti-Derp III antibodies isolated from the serum. Toproduce monoclonal antibodies, antibody-producing cells (lymphocytes)can be harvested from an immunized animal and fused by standard somaticcell fusion procedures with immortalizing cells such as myeloma cells toyield hybridoma cells. Such techniques are well known in the art, forexample the hybridoma technique originally developed by Kohler andMilstein, (Nature (1975) 256:495-497) as well as other techniques suchas the human B cell hybridoma technique (Kozbar et al., Immunology Today(1983) 4:72) and the EBV-hybridoma technique to produce human monoclonalantibodies (Cole et al., Monoclonal Antibodies and Cancer Therapy (1985)Alan R. Liss, Inc. pp. 77-96). Hybridoma cells can be screenedimmunochemically for production of antibodies specifically reactive witha peptide having an activity of Der p III and the monoclonal antibodiesisolated.

The term antibody as used herein is intended to include fragmentsthereof which are also specifically reactive with a peptide having anactivity of Derp III. Antibodies can be fragmented using conventionaltechniques and the fragments screened for utility in the same manner asdescribed above for whole antibodies. For example, F(ab′)₂ fragments canbe generated by treating antibody with pepsin. The resulting F(ab′)₂fragment can be treated to reduce disulfide bridges to produce Fab′fragments. The antibody of the present invention is further intended toinclude bispecific and chimeric molecules having an anti-Derp IIIportion.

Another aspect of this invention provides T cell clones and soluble Tcell receptors specifically reactive with a peptide having an activityof Der p III. Monoclonal T cell populations (i.e., T cells geneticallyidentical to one another and expressing identical T cell receptors) canbe derived from a subject sensitive to Derp III, followed by repetitivein vitro stimulation with a Der p III protein or peptide having anactivity of Der p III in the presence of MHC-matched antigen-presentingcells. Single Der p III MHC responsive cells can then be cloned bylimiting dilution and permanent lines expanded and maintained byperiodic in vitro restimulation. Alternatively, Der p III specific T-Thybridomas can be produced by a technique similar to B cell hybridomaproduction. For example, a mammal, such as a mouse, is immunized with apeptide having an activity of Der p III, T cells from the mammal can bepurified and fused with an autonomously growing T cell tumor line. Fromthe resulting hybridomas, cells responding to a peptide having anactivity of Der p III are selected and cloned. Procedures forpropagating monoclonal T cell populations are described in Cellular andMolecular Immunology (Abul K. Abbas et al., ed.), W. B. SaundersCompany, Philadelphia, Pa. (1991) page 139. Soluble T cell receptorsspecifically reactive with a peptide having an activity of Derp III canbe obtained by immunoprecipitation using an antibody against the T cellreceptor as described in Immunology: A Synthesis (Second Edition),Edward S. Golub et al., ed., Sinauer Associates, Inc., Sunderland, Mass.(1991) pages 366-369.

T cell clones specifically reactive with a peptide having an activity ofDer p III can be used to isolate and molecularly clone the gene encodingthe relevant T cell receptor. In addition, a soluble T cell receptorspecifically reactive with a peptide having an activity of Der p III canbe used to interfere with or inhibit antigen-dependent activation of therelevant T cell subpopulation, for example, by administration to asubject sensitive to Der p III. Antibodies specifically reactive withsuch a T cell receptor can be produced according to the techniquesdescribed herein. Such antibodies can be used to block or interfere withthe T cell interaction with peptides presented by MHC.

Exposure of allergic subjects to peptides having an activity of Der pIII and which have T cell stimulating activity may cause the appropriateT cell subpopulations to become non-responsive to the respective proteinallergen (e.g., fail to stimulate an immune response upon suchexposure). In addition, such administration may modify the lymphokinesecretion profile as compared with exposure to the naturally-occurringprotein allergen or portion thereof (e.g., result in a decrease of IL-4and/or an increase in IL-2). Furthermore, exposure to peptides having anactivity of Der p III which have T cell stimulating activity mayinfluence T cell subpopulations which normally participate in theresponse to the allergen such that these T cells are drawn away from thesite(s) of normal exposure to the allergen (e.g., nasal mucosa, skin,and lung) towards the site(s) of therapeutic administration of theprotein or fragment derived therefrom. This redistribution of T cellsubpopulations may ameliorate or reduce the ability of a subject'simmune system to stimulate the usual immune response at the site ofnormal exposure to the allergen, resulting in a diminution in allergicsymptoms.

A peptide having an activity of Derp III when administered to a subjectsensitive to house dust mites is capable of modifying the B cellresponse, T cell response, or both the B cell and the T cell response ofthe subject to the allergen. As used herein, modification of theallergic response of a subject to a house dust mite allergen can bedefined as non-responsiveness or diminution in symptoms to the allergen,as determined by standard clinical procedures (See e.g., Varney et al.,(1990) British Medical Journal 302:265-269), including diminution inhouse dust mite induced asthmatic symptoms. As referred to herein, adiminution in symptoms includes any reduction in the allergic responseof a subject to the allergen following a treatment regimen with apeptide of the invention. This diminution in symptoms may be determinedsubjectively (e.g., the subject feels more comfortable upon exposure tothe allergen), or clinically, such as with a standard skin test.

Peptides or antibodies of the present invention can also be used fordetecting and diagnosing sensitivity to Der p III. For example, thiscould be done by combining blood or blood products obtained from asubject to be assessed for sensitivity with a peptide having an activityof Der p III, under conditions appropriate for binding of components inthe blood (e.g., antibodies, T cells, B cells) with the peptide(s) anddetermining the extent to which such binding occurs. Other diagnosticmethods for allergic diseases which the peptides or antibodies of thepresent invention can be used include radio-allergosorbent test (RAST),paper radioimmunosorbent test (PRIST), enzyme linked immunosorbent assay(ELISA), radio immunoassays (RIA), immuno-radiometric assays (IRMA),luminescence immunoassays (LIA), histamine release assays and IgEimmunoblots.

In another assay, the presence in a subject of IgE specific for Der pIII and the ability of T cells of the subject to respond to T cellepitopes of Der p III can be determined by administering to the subjectan Immediate Type Hypersensitivity test and/or a Delayed TypeHypersensitivity test (see e.g., Immunology (1985) Roitt, I. M.,Brostoff, J., Male, D. K. (eds.), C. V. Mosby Co., Gower MedicalPublishing, London, NY, pp. 19.2-19.18; pp.22.1-22.10) utilizing apeptide having an activity of Der p III, or a modified form of a peptidehaving an activity of Derp III, each of which binds IgE specific for theallergen. The same subjects are administered a Delayed TypeHypersensitivity test prior to, simultaneously with, or subsequent toadministration of the Immediate Type Hypersensitivity test. Of course,if the Immediate Type Hypersensitivity test is administered prior to theDelayed Type Hypersensitivity test, the Delayed Type Hypersensitivitytest would be given to those subjects exhibiting a specific ImmediateType Hypersensitivity reaction. The Delayed Type Hypersensitivity testutilizes a peptide having an activity of Der p III which has human Tcell stimulating activity and which does not bind IgE specific for theallergen in a substantial percentage of the population of subjectssensitive to the allergen (e.g., at least about 75%). Those subjectsfound to have both a specific Immediate type Hypersensitivity reactionand a specific Delayed Type Hypersensitivity reaction are administeredan amount of a composition suitable for pharmaceutical administration.The composition comprises the peptide having an activity of Der p III asused in the Delayed Type Hypersensitivity test and a pharmaceuticallyacceptable carrier or diluent.

A peptide having an activity of Der p III can be used in methods oftreating and preventing allergic reactions to a house dust mite allergenor a cross-reactive protein allergen. Thus, the present inventionprovides compositions suitable for pharmaceutical administrationcomprising an amount of at least one peptide having an activity of DerpIII and a pharmaceutically acceptable carrier. Administration of thecompositions of the present invention to a subject to be desensitizedcan be carried out using known procedures, at dosages and for periods oftime effective to reduce sensitivity (i.e., reduce the allergicresponse) of the subject to house dust mite. The term subject isintended to include living organisms in which an immune response can beelicited, e.g., mammals. Examples of subjects include humans, dogs,cats, mice, rats, and transgenic species thereof. An amount of at leastone peptide having an activity of Der p III necessary to achieve atherapeutic effect may vary according to factors such as the degree ofsensitivity of the subject to house dust mite, the age, sex, and weightof the subject, and the ability of a peptide having an activity of Der pIII to elicit an antigenic response in the subject. Dosage regima may beadjusted to provide the optimum therapeutic response. For example,several divided doses may be administered daily or the dose may beproportionally reduced as indicated by the exigencies of the therapeuticsituation.

The active compound (i.e., at least one peptide having an activity ofDerp III) may be administered in a convenient manner such as byinjection (subcutaneous, intravenous, etc.), oral administration,inhalation, transdermal application, or rectal administration. Dependingon the route of administration, the active compound may be coated in amaterial to protect the compound from the action of enzymes, acids andother natural conditions which may inactivate the compound.

To administer a peptide having an activity of Der p III by other thanparenteral administration, it may be necessary to coat the peptide with,or co-administer the peptide with, a material to prevent itsinactivation. For example, a peptide having an activity of Der p III maybe administered to a subject in an appropriate carrier, diluent oradjuvant, co-administered with enzyme inhibitors or in an appropriatecarrier such as liposomes. Pharmaceutically acceptable diluents includesaline and aqueous buffer solutions. Adjuvant is used in its broadestsense and includes any immune stimulating compound such as interferon.Adjuvants contemplated herein include resorcinols, non-ionic surfactantssuch as polyoxyethylene oleyl ether and n-hexadecyl polyethylene ether.Enzyme inhibitors include pancreatic trypsin inhibitor,diisopropylfluorophosphate (DEP) and trasylol. Liposomes includewater-in-oil-in-water CGF emulsions as well as conventional liposomes(Strejan et al., (1984) J. Neuroimmunol. 7:27). For purposes of inducingT cell non-responsiveness, the composition is preferably administered innon-immunogenic form, e.g., one that does not contain adjuvant.

The active compound may also be administered parenterally orintraperitoneally. Dispersions can also be prepared in glycerol, liquidpolyethylene glycols, and mixtures thereof and in oils. Under ordinaryconditions of storage and use, these preparations may contain apreservative to prevent the growth of microorganisms.

Pharmaceutical compositions suitable for injectable use include sterileaqueous solutions (where water soluble) or dispersions and sterilepowders for the extemporaneous preparation of sterile injectablesolutions or dispersion. In all cases, the composition must be sterileand must be fluid to the extent that easy syringability exists. It mustbe stable under the conditions of manufacture and storage and must bepreserved against the contaminating action of microorganisms such asbacteria and fungi. The carrier can be a solvent or dispersion mediumcontaining, for example, water, ethanol, polyol (for example, glycerol,propylene glycol, and liquid polyetheylene glycol, and the like),suitable mixtures thereof, and vegetable oils. The proper fluidity canbe maintained, for example, by the use of a coating such as lecithin, bythe maintenance of the required particle size in the case of dispersionand by the use of surfactants. Prevention of the action ofmicroorganisms can be achieved by various antibacterial and antifungalagents, for example, parabens, chlorobutanol, phenol, ascorbic acid,thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, sodium chloride, orpolyalcohols such as mannitol and sorbitol, in the composition.Prolonged absorption of the injectable compositions can be brought aboutby including in the composition an agent which delays absorption, forexample, aluminum monostearate or gelatin.

Sterile injectable solutions can be prepared by incorporating activecompound (i.e., at least one peptide having an activity of Der p III) inthe required amount in an appropriate solvent with one or a combinationof ingredients enumerated above, as required, followed by filteredsterilization. Generally, dispersions are prepared by incorporating theactive compound into a sterile vehicle which contains a basic dispersionmedium and the required other ingredients from those enumerated above.In the case of sterile powders for the preparation of sterile injectablesolutions, the preferred methods of preparation are vacuum drying andfreeze-drying which yields a powder of the active ingredient (i.e., atleast one peptide having an activity of Der p III) plus any additionaldesired ingredient from a previously sterile-filtered solution thereof.

When the peptide having an activity of Der p III is suitably protected,as described above, the peptide may be orally administered, for example,with an inert diluent or an assimilable edible carrier. The peptide andother ingredients may also be enclosed in a hard or soft shell gelatincapsule, compressed into tablets, or incorporated directly into thesubject's diet. For oral therapeutic administration, the active compoundmay be incorporated with excipients and used in the form of ingestibletablets, buccal tablets, troches, capsules, elixirs, suspensions,syrups, wafers, and the like. The percentage of the active ingredient inthe compositions and preparations may, of course, be varied and mayconveniently be between about 5 to about 80% of the weight of the unit.The amount of active compound in such therapeutically usefulcompositions is such that a suitable dosage will be obtained.

As used herein “pharmaceutically acceptable carrier” includes any andall solvents, dispersion media, coatings, antibacterial and antifungalagents, isotonic and absorption delaying agents, and the like. The useof such media and agents for pharmaceutically active substances is wellknown in the art. Except insofar as any conventional media or agent isincompatible with the active compound, use thereof in the compositionssuitable for pharmaceutical administration is contemplated.Supplementary active compounds can also be incorporated into thecompositions.

It is especially advantageous to formulate parenteral compositions indosage unit form for ease of administration and uniformity of dosage.Dosage unit form as used herein refers to physically discrete unitssuited as unitary dosages for the mammalian subjects to be treated; eachunit containing a predetermined quantity of active compound calculatedto produce the desired therapeutic effect in association with therequired pharmaceutical carrier. The specification for the dosage unitforms of the invention are dictated by and directly dependent on (a) theunique characteristics of the active compound and the particulartherapeutic effect to be achieved, and (b) the limitations inherent inthe art of compounding such an active compound for the treatment ofsensitivity in subjects.

The invention also provides a composition comprising at least twopeptides having an activity of Der p III (e.g., a physical mixture of atleast two peptides), each having T cell stimulating activity.Alternatively, a peptide having at least two regions, each having T cellstimulating activity (i.e., each region comprising at least one T cellepitope) can be administered to an allergic subject. A composition oftwo peptides having a Derp III activity or a composition of two peptideshaving at least two regions, each having T cell stimulating activity canbe administered to a subject in the form of a composition with apharmaceutically acceptable carrier as hereinbefore described. An amountof one or more of such compositions can be administered simultaneouslyor sequentially to a subject sensitive to a house dust mite allergen totreat such sensitivity.

The cDNA (or the mRNA which served as a template during reversetranscription) encoding a peptide having an activity of Derp III can beused to identify similar nucleic acids in any variety or type of animaland, thus, to molecularly clone genes which have sufficient sequencehomology to hybridize to the cDNA encoding a peptide having an activityof Derp III. Thus, the present invention includes not only peptideshaving an activity of Derp III, but also other proteins which may beallergens encoded by DNA which hybridizes to DNA of the presentinvention.

Isolated peptides that are immunologically related to Der p III, such asby antibody cross-reactivity or T cell cross-reactivity, other thanthose already identified, are within the scope of the invention. Suchpeptides bind antibodies specific for the protein and peptides of theinvention, or stimulate T cells specific for the protein and peptides ofthis invention.

A peptide having an activity of Derp III (i.e., Derp III producedrecombinantly or by chemical synthesis) is free of all other house dustmite proteins and, thus, is useful in the standardization of allergenextracts which are key reagents for the diagnosis and treatment of housedust mite hypersensitivity. In addition, such a peptide is of aconsistent, well-defined composition and biological activity for use inpreparations that will be administered for therapeutic purposes (e.g.,to modify the allergic response of a subject sensitive to house dustmite). Such peptides can also be used to study the mechanism ofimmunotherapy of D. pteronyssinus allergy and to design modifiedderivatives or analogs useful in immunotherapy.

Work by others has shown that high doses of allergen extracts generallyproduce the best results during immunotherapy (i.e., best symptomrelief). However, many subjects are unable to tolerate large doses ofsuch extracts due to systemic reactions elicited by the allergens andother components within these preparations. A peptide having an activityof Der p III has the advantage of being free of all other mite protein.Thus, such a peptide can be administered for therapeutic purposes withfewer anticipated side effects.

It is now also possible to design an agent or a drug capable of blockingor inhibiting the ability of a house dust mite allergen to induce anallergic reaction in sensitive subjects. Such agents could be designed,for example, in such a manner that they would bind to relevant anti-DerpIII IgE molecules, thus preventing IgE-allergen binding, and subsequentmast cell/basophil degranulation. Alternatively, such agents could bindto cellular components of the immune system, resulting in suppression ordesensitization of the allergic responses to house dust mite allergens.A non-restrictive example of this is the use of peptides including B orT cell epitopes of Der p III or modifications thereof, based on the cDNAprotein structure of Der p III to suppress the allergic response to ahouse dust mite allergen. This could be carried out by defining thestructures of fragments encoding B and T cell epitopes which affect Band T cell function in in vitro studies with blood components fromsubjects sensitive to house dust mite.

The invention is further illustrated by the following examples whichshould not be construed as further limiting the subject invention. Thecontents of all references and published patent applications citedthroughout this application are hereby incorporated by reference.

The following methodology was used throughout the Examples.

EXAMPLES

Materials and Methods

D. pteronyssinus Cultures

Whole mites were purchased from the Commonwealth Serum Laboratories,Parkville, Australia and spent medium was a gift from the same source.

Purification of Native Der p III

Using a method adapted from Heymann et al. (Heymann et al. J AllergyClin Immunol (1989) 83: 1055-1067), 15 ml of a 50-80% saturated ammoniumsulfate precipitate of D. pteronyssinus spent growth medium was appliedto an upward flowing, 2 cm x 90 cm polyacrylamide P-100 columnequilibrated in PBS (Pharmacia, LKB Biotechnology, Uppsala, Sweden). Theprotein content of the eluted 5 ml fractions was determined by measuringoptical density (A280 nm) and analysis by SDS-PAGE. Those fractionscontaining predominantly bands in the 30 kDa region were pooled,concentrated by polyethylene glycol 6000 (BDH Chemicals, Aust. PTY. Ltd.Kilsyth, Vic. Aust), dialyzed against PBS and passed over the columnagain. This was repeated twice until the analysis by SDS-PAGE determinedthat the only bands detectable were a doublet of approximately molecularweight 30 kDa.

Protein Sequence Analysis

The affinity purified native Der p III and Der f III proteins weresubjected to HPEC using a 12% column system (Applied Biosystems, FosterCity, CA). The affinity purified proteins or the HPEC fractions of theappropriate molecular weight were then subjected to protein sequenceanalysis using Applied Biosystems model 477A gas-phase sequenator withon-line phenylthiohydantoin derivative analysis (model 120).Alternatively, the affinity purified proteins were first separated bySDS-PAGE (BioRad), transferred to Problot (Applied Biosystems) andsequenced using a Beckman model LF300. After initial sequence analysisof the proteins, o-phthalaldehyde was applied to block N-termini exceptthose with prolines (position 13 for Der p III) to eliminatecontaminating peptide sequences and extend the N-terminal sequenceunambiguously. The CNBr peptides were produced by cleaving the affinitypurified proteins with 2% (w/v) CNBr in 70% (w/v) formic acid overnightat room temperature. The digested peptides were subjected to HPEC forpurification and then the peptide fragments were subjected to sequenceanalysis.

Preferred Codon Usage

The codon usage bias for the mature proteins Der f I (Dilworth et al.Clin Exp Allergy (1991) 21:25-32), Der f II (Trudinger et al. Clin ExpAllergy (1991) 21:33-37), Derp I (Chua et al. J Exp Med (1988)167:175-182) and Derp II (Chua et al. Int Arch Allergy Appl Immunol(1990) 21:118-123) was determined. The average percent usage of eachtriplet codon for each amino acid was determined for each of these fourDermatophagoides proteins and the results tabulated in Table 1. TABLE 1Preferred codon usage table for Dermatophagoides allergens. Amino acidCodon % Ala A GCT 45.4 GCC 33 GCA 21.6 GCG 0 Cys C TGT 55.2 TGG 44.8 AspD GAT 92.3 GAG 7.7 Glu E GAA 100 GAG 0 Phe F TTC 82.5 TTT 17.5 Gly G GGT65.2 GGA 24.5 GGC 10.3 GGG 0 His H CAT 78.8 CAC 21.2 Ile I ATT 50 ATC48.5 ATA 1.5 Lys K AAA 99 AAG 1 Leu L TTG 64.5 TTA 18.5 CTC 8 CTT 6.5CTG 2.5 CTA 0 Met M ATG 100 Asn N AAT 52 AAG 48 Pro P CGA 87.2 CCC 9.6CCG 3.2 CCT 0 Gln Q CAA 94.4 CAG 5.6 Arg R CGA 36.5 CGT 41.6 CGC 16.5AGA 5.4 CGG 0 AGG 0 Ser S TCA 42.5 TCT 18.4 AGT 11.2 TCG 11.2 AGC 10.2TCC 6.5 Thr T ACT 39.2 ACA 35 ACC 18.9 ACG 6.9 Val V GTT 51.2 GTC 33.8GTA 12.3 GTG 2.7 Trp W TGG 100 Tyr Y TAT 62 TAC 38 Stop TAA 75 TGA 25TAG 0Construction of the D. pteronyssinus λ gt10 cDNA Library

Polyadenylated mRNA (10 μg) was used to synthesize cDNA by the RNase Hmethod (Gubler et al. Gene (1983) 25:263-269) using a kit (AmershamInternational, Aylesbury, U.K.). After the addition of EcoRI restrictionenzyme linkers (New England Biolabs, Beverly, U.S.A.), the cDNA wasligated to alkaline-phosphatase treated lambda gt10 arms (PromegaBiotec, Madison, Wis.). The recombinant phage DNA was packaged andplated out in E. coli JP777 to produce a library of 5×10⁵ recombinants.

Kinase End-labeling of Oligonucleotides

Oligonucleotides were synthesized using an Applied Biosystem PCR mate(Applied Biosystems, Foster City, Calif.). Twenty picomole ofoligonucleotide DNA was end labeled with (γ-³²P) ATP using T4polynucleotide kinase (Promega Corp., Madison, Wis.) (Maniatis, T.,Fritsch, E. F. and Sambrook, J. Molecular Cloning: A Laboratory Manual.2nd Ed. Cold Spring Harbor Laboratory Press, 1989). Labeledoligonucleotide was purified by 15% polyacrylamide gel electrophoresisand subsequently eluted into sterile distilled water.

Isolation of Der p III cDNA Clones from the X gt10 cDNA Library

Screening of the library was performed with two probes designed usingboth N-terminal and internal protein sequence data obtained as describedabove for the group III allergens. The first, P3forward3 (P3F3), was a38 mer in length with the following nucleotide sequence,5′TCAGAAAAAGCTTTGGCTGGTGAATCACCATATCAAAT 3′ (SEQ ID NO:8). The secondprobe, P3reverse4(P3R4), a 41 mer with the following nucleotidesequence, 5′GAATCAACACCACCATTAGCAACATCACCACCGCAAATCAT3′ (SEQ ID NO:9).The library was plated at 25,000 pfu per 150 mm petri dish and the phagewere lifted onto nitrocellulose (Schleicher & Schuell, Dassel, Germany).Duplicate filter lifts from each plate were denatured and baked forhybridization with a different one of the two probes (Maniatis, T.,Fritsch, E. F. and Sambrook, J. Molecular Cloning: A Laboratory Manual.2nd Ed. Cold Spring Harbor Laboratory Press, 1989). Hybridizations wereperformed in hybridization mix (6× sodium chloride/sodium citrate pH 7.0(SSC), 0.1% Denhardts, 100 μg/ml denatured herring sperm DNA) at 42° C.with 10⁶ cpm/ml labeled probe overnight. Filters were washed three timesat 42° C. for 20 min and then at 50° C. for 10 min, in 400 ml washsolution containing 6×SSC, 0.1% Triton X-100.

Isolation of DNA from λgt10 Der p III Clones

Phage DNA from the Der p III clones was prepared using a polyethyleneglycol precipitation procedure (Chua et al., J Exp Med (1988)167:175-182).

Subcloning and DNA Sequencing

Purified Der p III phage DNA was digested with EcoRI restriction enzyme(Toyobo) and the released fragment ligated to EcoRI restriction enzymedigested M13mp19 sequencing vector (Messing, Meth. Enzymol. (1983) 101:20-78). The recombinant DNA was transformed using E. coli TG-1 andsequencing performed using the dideoxynucleotide chain terminationmethod and Sequenase (U.S. Biochemicals) (Sanger et al., Proc Natl AcadSci USA (1977) 74:5463-5467). The oligonucleotide primers used forsequencing included the universal primers, a 7-mer sequencing primer

-   -   (−40)5′ CAGCACTGACCCTTTTG3′ (SEQ ID NO:4) and a 16-mer reverse        sequencing primer (−24)5′ AACAGCTATGACCATG3′ (SEQ ID NO: 5), the        two internal primers used for the library screening (SEQ ID NOS:        8 and 9) and two internal primers P3forward5(P3F5)        5′AAAGCTGTTGGATTACCA3′ (SEQ ID NO:6) and P3reverse5(P3R5)        5′TACATCCGATCCTTTTGC3′ (SEQ ID NO:7) and P3F4        5′GCGGATCCATTGTTGGTGGT 3′ (SEQ ID NO: 18). The two internal        probes were designed to correspond to nucleotide residues        456-473 (P3F5) and 491-474 (P3R5) (FIG. 1.). The primers were        used to sequence the isolated clone in both orientations.        DNA and Protein Sequence Analysis

Sequence analysis was performed using the MAC VECTOR software (IBI, NewHaven, U.S.A.). Computation for sequence homology with other proteinswas performed at the NCBI using the BLAST network service. The versionof BLAST used was BLAST 1.3.1OMP (7 Jul. 1993).

EXAMPLE 1 Sequence of the Native Group III Allergens

The protein isolation procedure produced a Der p III sample which ran asa doublet with molecular weights 30 and 28 k when analyzed by SDS-PAGE.Both bands reacted with polyclonal mouse anti-Der f III in accord withthe interspecies cross-reactivity previously reported (Thomas et al.,Exp. Appl. Acarol. (1992) 16:153-164). Der f III isolated from a 5A12monoclonal antibody (Heymann et al. J. Allergy Clin. Immun. (1989):1055-1067) column exhibited similar characteristics. Using theo-pthalaldehyde to eliminate the contaminating protein sequences, theN-terminal sequencing of both native Der p III and Der f III correctedand extended the known Der p III sequence and extended the Der f IIIsequence. The Der p III N-terminal sequence was extended toIVGGEKALAGQSPYQISLQSSSHFSGGTIL (SEQ ID NO:16). The Der f IlI N-terminalsequence was extended to IVGGVKAKAGDSPYQISLQSSSHFXGGSILD (SEQ ID NO:15). Comparison of the sequence data published by Stewart et al.(Immunology (1992) 75: 29-35) and Heymann et al., (J. Allergy. Clin.Immunol (1989) 83: 1055-1067) for the group III allergens with the dataherein indicated several errors in the published sequence. Inparticular, a non-conservative change at residue 8 from a positivelycharged lysine to a non-polar hydrophobic leucine was found (Der f III,Heymann et al., J Allergy Clin Immunol (1989) 83: 1055-1067). Twointernal peptides of Der f III were isolated by HPEC after CNBrdigestion of the natural protein, MICGGDVANGGVDSEQGD (SEQ ID NO: 10) andMTLDQTNAKPVPLPTS (SEQ ID NO:12).

EXAMPLE 2 Sequence of Recombinant Der p III

The protein sequence information obtained as described in Example 1 wasused in conjunction with the preferred codon usage data (Table 1) toconstruct two oligonucleotides probes. These oligonucleotides weredesigned to hybridize to nucleotide residues 159-196 and to residues688-648 of the Derp III clone (FIG. 2). Only clones which hybridizedstrongly with both probes were isolated from the λ gt10 cDNA library.The resulting nucleotide sequence for the P3WS1 clone and the deducedamino acid sequence is shown in FIG. 1. The complete nucleotide sequencewas 1059 bp in length. This includes a 5′ non-coding region of 62 bp, a211bp 3′ untranslated region and an open reading frame of 786 bp with astop codon (TGA) at nucleotide residues 846-848. There is no poly A tailbut there does appear to be a polyadenylation signal (AATAAA). The openreading frame encodes a protein which includes a 29 amino acid pre-proregion and starting at the N-terminal isoleucine, a mature protein of232 amino acid residues with a calculated molecular weight of 24,985 andpI of 8.5. The methionine residue (ATG) at amino acid position −29 isthe most likely translation initiation site. Selection for thisinitiation site was based in part on the presence of a sequencefollowing the methionine which encodes a classical signal peptide of 18amino acid residues with predominantly hydrophobic residues present. Inaddition, the immediate sequence prior to this ATG codon, 5′GAAAGATG3′,conforms loosely to the Kozak consensus sequence (CCACCATG) for theeucaryotic translation initiation site with the crucial purine (mostoften A) at the −3 position (Kozak, Nucleic Acid Research (1984)12:857-872).

The protein sequencing data of Derp III described in Example 1 differsfrom the amino acid sequence deduced from the cDNA of the P3WS1 clone asa result of the substitutions of Glu/Gln at residue 11 and a possibleCys/Ser substitution at residue 17. These substitutions may be due tothe existence of Der p III in different isoforms. Analysis of thededuced protein sequence for Der p III P3WS 1 confirmed that theposition of the Der f III CNBr peptide 1 (MI(C)GGDVANGGVDS(E)QGD) (SEQID NO:10) was correctly predicted to be from amino acid residues 177-183and has 88% identity with the recombinant sequence in this region,MICGGDVANGGKDSCQD (SEQ ID NO: 11). Interestingly, there are twoidentical non-conservative changes that exist when the native Der f IIIpeptide sequence is aligned with the P3WS1 clone sequence. There is achange from a non-polar hydrophobic valine at 178 (according tonumbering in FIG. 1) in Der f III to a positively charged lysine residuein the P3WS1 clone sequences. The other change is a glutamic acidresidue at 181 in the Der f III substituted for a cysteine residue inthe P3WS 1 clone sequence. The cysteine forms one of the disulfidebridges in both these and most other trypsin proteins. The predictedalignment of the second Der f III peptide, (M)TLDQTNA(K)PVPL(P)(T)(S)(SEQ ID NO:12), produced by the CNBr digestion was from amino acidresidues 95-110 (MKLNQKNAKAVGLPAK) (SEQ ID NO: 13). There is 63%homology with the P3WS1 clone in this region. These differences betweenthe Der p III and Der f III protein sequences are consistent with the20% sequence variation found between other homologous allergens fromthis species such as the Der p I and Der f I; and Der p II and Der f II.

The complete sequence for the Der p III P3 WS1 clone encodes a proteinof 319 amino acids. Der p III, like all known trypsins, is synthesizedas a pre-pro zymogen. The cleavage site of the signal peptide ispostulated to be between amino acid residues −12 and −11 as the residuesaround this site conform to the amino acid constraints outlined by vonHeijne, (von Heijne, Eur J Biochem (1983) 133:17-21). Von Heijneproposed that small neutral amino acids are strongly preferred atpositions −1 and −3 from the cleavage site, such as the alanine andtyrosine seen in the Der p III gene. Proline residues are never found inpositions +1 to −3 thus excluding any other sites. Most mammaliantrypsin proteins have been reported to have pre or signal peptides of 15or 16 amino acids. The Der p III peptide is 18 amino acids in length.While the difference in length is relatively small, it does seem thatthe length of the signal peptide may be attributable to the phylogeneticdiversity of the species from which the trypsin originated. This is mostapparent in Streptomyces griseus with a 32 amino acid pre peptide (Kimet al., Biochem Biophys Res Commun (1991) 181:707-713). It has also beenreported that for mammalian trypsins the signal peptide contains twospecific clusters of two and then four hydrophobic residues (MacDonaldet al., J Biol Chem (1982) 257:9724-9732; Le Huerou et al, Eur J Biochem(1990) 193:767-73). There is an abundance of hydrophobic residues withinthis region of the Der p III gene but they are not arranged into highlyconserved clusters. The same is true of the signal peptides for bothDrosophila melangastor (Davis et al., Nucleic Acid Research (1988)13:6605-6615) and S. griseus (Kim et al., Biochem Biophys Res Commun(1991) 181:707-713). It is possible therefore that the highly conservedclusters of hydrophobic residues are not a characteristic of all trypsinproteins but rather that of mammalian trypsins.

Downstream from the signal peptide is the 11 residue pre-activationpeptide from amino acid residues −11 to −1. Comparison of this proregion with other pro regions from trypsins of various species indicatesthe Der p III pro peptide is unusual. Both vertebrate and invertebratetrypsins have been shown to have an octapeptide and or a hexapeptide proregion with four contiguous aspartyl residues followed by a lysineresidue at the -1 position (Le Huerou et al., Eur J Biochem (1990)193:767-73). It is the carboxyl region of this lysine residue which iscleaved during the activation of the trypsinogen to trypsin. The Der pIII lacks this polyaspartyl-lysine sequence. The trypsinogen thereforecan not be activated by the usual mechanism. There are a few othertrypsins which are similar to Der p III in this respect, D. melangastor(Davis et al., Nucleic Acid Research (1988) 13:6605-6615), S. griseus(Kim et al., Biochem Biophys Res Commun (1991) 181:707-713) and mostinterestingly, a 32 kDa anionic trypsin from the rat pancreas (Gendryand Launay, Biochemica et Biophysica Acta (1988) 955:243-249). Thisgroup showed that enterokinase, an enzyme which has a highly specificaffinity for the polyaspartyl-lysine residues in trypsin proteins, hadno effect on the trypsin that they isolated. They suggested thereforethat a different mechanism was being used for the activation process.The absence of any homology of the Der p III proenzyme region with anyof the known sequences may imply a unique activation mechanism.

A search of the protein database has confirmed that Der p III P3WS1 ishomologous to both vertebrate and invertebrate trypsins. The Der p IIIallergen is not a mite chymotrypsin (Gendry and Launay, Biochemica etBiophysica Acta (1988) 955:243-249) as comparison of the N-terminalprotein sequences showed that they differ by as much as 50%. FIG. 2shows a comparison of the amino acid sequences of Der p III P3WS1 andcrayfish trypsins (SEQ ID NOS: 2 and 3). The crayfish has 44% homologywith Der p III. There are seven cysteine residues, six of these residuesare known to form disulphide bridges, 54-70, 181-198 and 210-236 (FIG.2.) (Hartley, Phil Trans Roy Soc Lond B (1970) 257:77-87). Mostimportantly, the Der p III protein contains the highly conservedresidues involved in the catalytic activity and substrate specificity ofthe trypsin proteins. The conserved His 40 and Ser 185 (FIG. 1)represent the charge relay system which comprise the active catalyticsite of the trypsin enzyme. The positively charged aspartic acid residueat 179, represents the trypsin specificity site. Most serine proteaseshave a neutral amino acid at this residue (Keil, The Enzymes. AcademicPress, New York, 1971, pages 249-279). The glycine residues at 206 and211 in combination with the aspartic acid at 179 are responsible foraccommodating the bulky positively charged side chains of lysine andarginine, the substrate residues cleaved by trypsins. Amino acidresidues 179-185 and 202-206 (FIG. 1) form the S1 binding pockets whichare involved in the binding of the substrate to the trypsin molecule.The areas immediately surrounding all of these important residues arethe most conserved regions of the Der p III protein. All these resultsare consistent with the fact that among trypsin proteins from differentspecies structural variations occur in those regions of the moleculewhich are not important for catalytic activity (Vithayathil etal., ArchBiochem Biophys (1961) 92:532-540).

Most trypsin proteins generally have a common pairing of cysteineresidues to form six disulphide bridges, with two of these bridges, Cys15-145 and Cys 117-218 being unique to this group of proteins. Der p IIIlike both crayfish (Titani etal., Biochemistry (1983) 22:1459-1465) andS. griseus are missing these two unique links, but more importantly Derp III is unique as it contains an extra unpaired cysteine residue. Thisresidue may be the equivalent to Cys 15 in the bovine trypsin whichunlike, Cys 145, 117 and 218 was not eliminated during evolutionarydivergence of the mite trypsin.

The isolation of the gene encoding the nucleotide sequence for the groupIII allergen, Der p III is the first primary sequence determination forthis group of Dermatophagoides allergens. Comparison of the sequencewith other vertebrate and invertebrate serine proteases in view ofsubstrate binding experiments (Stewart et al., Immunology (1992)75:29-35; Ando et al., Arerugi (1992) 41:704-707), indicates that thegroup III allergens are trypsin proteins. Trypsin proteins are secretedas pre-pro zymogens by the pancreatic acinar cells of all vertebrate andinvertebrate species. Invertebrate trypsins have been reported to have amolecular weight ranging from 20 to 30 kDa (Graf et al., Insect Biochem(1985) 15:611-618). The Der p III P3WS1 trypsinogen has a calculatedmolecular weight of 28 kDa and the corresponding mature protein amolecular weight of 24,985 kDa while the native protein purified,existed as duplicate of 28 and 30 kDa as estimated by SDS-PAGE. Therehave been other reports of multiple protein bands being isolated forboth Derf III (Thomas et al, Exp Appl Acarol (1992) 16:153-164) and DerpIII (Stewart etal., Immunology (1992) 75:29-35). These results are notunusual as trypsin proteins are known to exist in several isoforms.Gendry and Launay (1988) isolated duplicate protein bands of an anionictrypsin-like protein from rat pancreas. They demonstrated that thehigher 32 kDa band represented the inactive trypsin and the lower 30 kDaband represented the active form of the trypsin which could autocatalyzethe cleavage of the 32 kDa band. It is therefore possible that the 30kDa band represents the inactive trypsinogen and the 28 kDa band theactive trypsin. The number of isozymes for invertebrate trypsins hasbeen reported to range from 1-12 (MacDonald et al. J Biol Chem (i982)257:9724-9732). Stewart et al. (1992) proposed nine major isoforms ofDer p III existed, with pI's ranging from 4 to >8.

EXAMPLE 3 Expression and Purification of Recombinant Der p III

A complementary DNA insert encoding Der p III (FIG. 1) was digested withEcoRI and inserted into pUC 19. To remove the non-translated 5′ sequenceas well as part of the putative hydrophobic leader, the cDNA was cleavedwith MscI and an EcoRI linker was added. Subsequently, the truncated Derp III fragment was EcoRI digested and subcloned into the expressionvector pET11d (Studier et al., Gene Expression Technology: Methods inEnzymology 185, Academic Press, San Diego, Calif. (1990) 60-89). Thesequence and reading frame were verified by DNA sequencing. The Der pIII coding sequence encompassed residue 13 to the stop codon (see FIG.1). The expression vector pET11d Der p III was transformed into the E.coli host strain BL21 (DE3) and selected on plates containing 150 μg/mlampicillin (Studier et al., Gene Expression Technology: Methods inEnzymology 185, Academic Press, San Diego, Calif. (1990) 60-89). Asingle transformant colony was grown up in 2 ml volume of BHIB mediumcontaining 150 μg/ml ampicillin at 37° C., for approximately 6 hr. Tenmilliliters of this culture was spread onto a selection plate and grownovernight at 37° C. The bacterial lawn was recovered in 2 ml media andadded to 500 ml of BHIB medium (150 μg/ml ampicillin) and grown at 37°C. to A₆₀₀=1.0. Recombinant expression was induced by the addition ofIPTG to a final concentration of 1 mM. After 2 hr growth, cells wereharvested, lysed and the proteins solubilized in 6 M guanidine HClbuffer containing 100 mM 2-ME as previously described for the ragweedrecombinant allergens, Amb a I.1 and Amb a II (Rogers, et al. (1991) J.Immunol, 147:2547-2552).

The guanidine HCl lysate containing Der p III was subjected to Ni²⁺metal-ion affinity chromatography under denaturing conditions in 8 Murea (Hochuli, E. et al., (1988) Bio/Technology 6:1321-1325). Afterelution from the Ni²⁺ chelating support, QIAGEN NTA-Agarose (Diagen GmH,Dusseldorf, Germany), the recombinant Derp III protein preparations weresubjected to SDS-PAGE analysis (FIG. 3).

Recombinant Der p III had an expected molecular weight of approximately27 kDa as predicted for the 252 amino acids plus amino acids used as apurification tag (MGHHHHHHEF (SEQ ID NO:17)). The pET11d expressionsystem and the Ni²⁺ methyl-ion-affinity chromatography method generatedapproximately 12 mg recombinant Der p III per liter of growth medium (asassessed by A₂₈₀ measurement). This expression and purification schemeyielded a protein preparation with purity exceeding 90% as assessed bySDS-PAGE visualized by Coomassie Blue staining. (FIG. 3). The observedapparent molecular weight of approximately 32 kDa is slightly higherthan that predicted from the primary structure (FIG. 1, and above). InFIG. 3, increasing concentrations of Der p III preparation were examinedto verify the purity (lane 1, 4.3 μg; lane 2, 8.7 μg; lane 3, 13.8 μg;lane 4, 17.4 μg; markers are indicated by M).

Equivalents

Those skilled in the art will recognize or be able to ascertain using nomore than routine experimentation, numerous equivalents to the specificembodiments described herewith. Such equivalents are considered to bewithin the scope of this invention and are encompassed by the followingclaims.

1-47. (canceled)
 48. An isolated peptide of a Derp III protein allergencomprising the amino acid sequence of SEQ ID NO:2, wherein the peptidecomprises at least one epitope of said protein allergen, and wherein theepitope is selected from the group consisting of a T cell epitope and aB cell epitope.
 49. An isolated peptide of a Derp III protein allergenencoded by the nucleic acid comprising the nucleotide sequence of SEQ IDNO: 1, wherein the peptide comprises at least one epitope of saidprotein allergen, and where the epitope is selected from the groupconsisting of a T cell epitope and a B cell epitope.
 50. The isolatedpeptide of claim 48 which is produced by recombinant expression of anucleic acid.
 51. The isolated peptide of claim 48 which is produced bychemical synthesis.
 52. An isolated peptide of a Derp III proteinallergen, wherein the peptide comprises at least one T cell epitope ofsaid protein allergen and wherein the epitope is recognized by a T cellreceptor specific for a Der p III protein allergen comprising the aminoacid sequence of SEQ ID NO:2.
 53. An isolated peptide of a Derp IIIprotein allergen, wherein the peptide comprises at least one epitope ofsaid protein allergen and wherein the epitope is capable of stimulatingT cells specific for a Der p III protein allergen comprising the aminoacid sequence of SEQ ID NO:2.
 54. A method of detecting sensitivity tohouse dust mite protein allergens in a mammal sensitive to said proteinallergens, comprising administering to said mammal the isolated peptideof claim 48, detecting the presence of an allergic response in saidmammal, and correlating the allergic response with the presence of saidpeptide in the individual.
 55. A method of treating sensitivity to housedust mite protein allergens in a mammal sensitive to such proteinallergens, comprising administering to said mammal a therapeuticallyeffective amount of the isolated peptide of claim 48.